The aim of this project is to determine the primary structure of telomeres and adjacent sequences - the regions at the ends of chromosomes - of rotifers of the ancient ameiotic class Bdelloidea and to compare it with that of rotifers of the facultatively sexual sister class, the Monogononta. As bdelloid rotifers have evolved for many millions of years without meiosis and because chromosome ends of sexually reproducing species play an important and specific role in meiosis, it is expected that the proposed study will reveal features of chromosome ends specifically involved in meiosis. Because of this and also because it has been found that bdelloid rotifers lack the simple sequence repeats found at the chromosome ends of nearly all sexually-reproducing species, it is also expected that bdelloid chromosome ends will be found to have novel structures the elucidation of which will add importantly to our knowledge of telomere function and evolution. The chromosomal end-regions of three species of bdelloids and two species of monogononts will be cloned and sequenced, employing a novel procedure for the selection of clones containing chromosome ends, regardless of whether they do or do not contain the simple sequence repeats characteristic of telomeres commonly found in other species. As telomeres are involved in diverse pathologies, including metastatic growth, the results of the proposed study may provide insight into mechanisms and possible therapies of importance.